The use of certain organopolysiloxane-based silicone release compositions to form release coatings on the surface of various substrates is known in the art. These substrates include paper, cardboard, laminated paper, synthetic resin films, fabrics, synthetic fibers, metal foils, and the like. Cured coatings capable of releasing a variety of tacky substances are formed by coating the surface of the substrate with an organopolysiloxane-based silicone release composition and thereafter curing the composition.
One drawback generally associated with dimethylpolysiloxane-based silicone release compositions is the very light release resistance of the coatings afforded by their cure. This has made it necessary to add a controlled-release additive to these compositions with the goal of adjusting the release resistance of their cured coatings. These controlled-release additives are exemplified by MQ silicone copolymers comprised of R'.sub.3 SiO.sub.3/2 and SiO.sub.4/2 units wherein R' represents monovalent hydrocarbon groups having no more than 2 carbons as set forth in U.S. Pat. No. 3,527,659 and European Patent No. 0108208 and by MQ silicone copolymers comprised of the R'SiO.sub.1/2, (CH.sub.2 .dbd.CH)R'.sub.2 SiO.sub.1/2, and SiO.sub.4/2 units wherein R' represents monovalent hydrocarbon groups having no more than 2 carbons as set forth in Canadian Patent No. 1064640.
Unfortunately, silicone release compositions containing the above-described MQ silicone copolymers as a controlled-release additive suffer from a large migration of silicone component into the tacky substance, which results in a substantial decline in the residual adhesion of the tacky substance. Another problem arises from the fact that the above-described MQ silicone copolymers are generally solids at room temperature. As a consequence, the silicone release compositions that contain these MQ silicone copolymers have an elevated viscosity, which degrades their coatability on the surface of various substrates.
It is an object of the present invention the introduction of silicone release compositions that yield cured release coatings that exhibit excellent release properties against tacky substances without impairing the residual adhesion of said tacky substances.